My best friend and I had been close since the seventh grade. Seven months ago, I met her boyfriend. He was cute and funny and great to be with. In fact, we'd talk online every once and awhile. Unfortunately, a few months ago my friend and I had a huge falling out and we still aren't speaking. As of a month ago, her now ex-boyfriend and I started talking much more often and we have developed mutual feelings for each other. They still talk on occasion, but he hasn't said anything to her. Even though they broke up just before our falling out and although it was definitely mutual, I still feel guilty. Should we tell her?
—Crushing and Concerned Cassie
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Dear Crushing and Concerned in Cassie,
This is definitely a difficult situation. When it comes to dating a best friend's ex-boyfriend or crush, the code of rules is really complicated. Half the time we won't allow it, and the rest of the time we find a loophole. My general rule is don't do it unless you are absolutely in love and even that can get you in trouble, but at least it'll be worth it.
Since you and your friend are on the outs, she might see your relationship with her ex-boyfriend as a way of hurting her. Best friends often fight, but many are able to get past their differences in the end. Make sure that before you pursue a deeper relationship with this guy or decide to tell your friend, you're willing to potentially damage your friendship permanently.
Since she's still talking to her ex, it's likely that she'll find out about your relationship sooner than later. Your past fight might be forgivable, but sneaking around with her ex may not be. She'll be angry either way, but if you're direct and honest with her, it might be something you two can eventually work through. Either she'll forgive you or she won't, but at least you can sleep well knowing that you've been honest. Best of luck!